feat: 优化 overlay_pixels

src/mscanvas.rs

@@ -290,23 +290,28 @@ impl MSCanvas {
 
     pub fn overlay_pixels(&mut self, canvas: &MSCanvas) -> Vec<u8> {
         let mut pixels = canvas.get_pixels();
+        let width = canvas.width.min(self.width) as usize;
+        let height = canvas.height.min(self.height) as usize;
 
-        let width = canvas.width.min(self.width);
-        let height = canvas.height.min(self.height);
+        // 预计算步长，避免重复计算
+        let src_stride = self.width as usize * 4;
+        let dst_stride = width * 4;
 
         for y in 0..height {
+            let src_base = y * src_stride;
+            let dst_base = y * dst_stride;
+
+            // 使用显式循环，可能被编译器自动向量化
             for x in 0..width {
-                let index = ((y * width + x) * 4) as usize;
+                let src_idx = src_base + x * 4;
+                let dst_idx = dst_base + x * 4;
 
-                // 跳过透明像素
-                if self.pixels[index + 3] == 0 {
-                    continue;
+                // 只在非透明时复制
+                if self.pixels[src_idx + 3] != 0 {
+                    // 一次复制4个字节（可能被优化为单个u32操作）
+                    pixels[dst_idx..dst_idx + 4]
+                        .copy_from_slice(&self.pixels[src_idx..src_idx + 4]);
                 }
-
-                pixels[index] = self.pixels[index];
-                pixels[index + 1] = self.pixels[index + 1];
-                pixels[index + 2] = self.pixels[index + 2];
-                pixels[index + 3] = self.pixels[index + 3];
             }
         }
 
@@ -418,6 +423,12 @@ impl MSCanvas {
         }
     }
 
+    pub fn fill_pixels_i32(&mut self, points: Vec<Point<i32>>) {
+        for point in points {
+            self.fill_pixel_at1(point.x, point.y);
+        }
+    }
+
     pub fn stroke_cross(&mut self, point: Point) {
         let Point { x, y } = point;
         let r = 10;
@@ -1280,10 +1291,10 @@ impl MSCanvas {
         }
     }
 
-    /// 填充一个简单多边形（支持凹多边形）
-    pub fn fill_polygon(&mut self, points: &[Point]) {
+    fn rasterize_polygon(&mut self, points: &[Point]) -> Vec<Point<i32>> {
+        let mut result = Vec::new();
         if points.len() < 3 {
-            return;
+            return result;
         }
 
         // 计算 y 范围
@@ -1330,7 +1341,7 @@ impl MSCanvas {
                     let x_start = active_edges[i].x.ceil() as i32;
                     let x_end = active_edges[i + 1].x.floor() as i32;
                     for x in x_start..=x_end {
-                        self.fill_pixel_at1(x, y);
+                        result.push(Point::new(x, y));
                     }
                 }
             }
@@ -1340,6 +1351,14 @@ impl MSCanvas {
                 edge.x += edge.dx_dy;
             }
         }
+
+        result
+    }
+
+    /// 填充一个简单多边形（支持凹多边形）
+    pub fn fill_polygon(&mut self, points: &[Point]) {
+        let filled_points = self.rasterize_polygon(points);
+        self.fill_pixels_i32(filled_points);
     }
 
     pub fn begin_path(&mut self) {
@@ -1385,8 +1404,8 @@ impl MSCanvas {
         }
 
         // 考虑矩形四边出界的情况
-        let w = (rect.w as i32).min(self.width - x).min(rect.w + x);
-        let h = (rect.h as i32).min(self.height - y).min(rect.h + y);
+        let w = (rect.w).min(self.width - x).min(rect.w + x);
+        let h = (rect.h).min(self.height - y).min(rect.h + y);
 
         if w == 0 || h == 0 {
             return;
@@ -1407,14 +1426,17 @@ impl MSCanvas {
         let width = self.width as usize;
 
         for dy in 0..h {
-            let src_start = ((dy + src_offset_y) * rect.w as usize + src_offset_x) * 4;
-            let dst_start = ((y + dy) * width + x) * 4;
+            for dx in 0..w {
+                let src_index = ((dy + src_offset_y) * rect.w as usize + dx + src_offset_x) * 4;
+                if rect.pixels[src_index + 3] == 0 {
+                    continue;
+                }
+                let dst_index = ((y + dy) * width + x + dx) * 4;
 
-            // 使用 unsafe 块进一步优化（如果确定索引安全）
-            unsafe {
-                let src_slice = &rect.pixels.get_unchecked(src_start..src_start + w * 4);
-                let dst_slice = self.pixels.get_unchecked_mut(dst_start..dst_start + w * 4);
-                dst_slice.copy_from_slice(src_slice);
+                self.pixels[dst_index] = rect.pixels[src_index];
+                self.pixels[dst_index + 1] = rect.pixels[src_index + 1];
+                self.pixels[dst_index + 2] = rect.pixels[src_index + 2];
+                self.pixels[dst_index + 3] = rect.pixels[src_index + 3];
             }
         }
     }